pointer masking: Support _smmpm to --isa

disasm/isa_parser.cc

@@ -318,6 +318,8 @@ isa_parser_t::isa_parser_t(const char* str, const char *priv)
       extension_table[EXT_ZICFILP] = true;
     } else if (ext_str == "zicfiss") {
       extension_table[EXT_ZICFISS] = true;
+    } else if (ext_str == "smmpm") {
+      extension_table[EXT_SMMPM] = true;
     } else if (ext_str.substr(0, 3) == "zvl") {
       reg_t new_vlen;
       try {

riscv/isa_parser.h

@@ -82,6 +82,7 @@ typedef enum {
   EXT_ZICFILP,
   EXT_ZICFISS,
   EXT_SSDBLTRP,
+  EXT_SMMPM,
   NUM_ISA_EXTENSIONS
 } isa_extension_t;